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File Server and Web Server Patterns

We’ll now check the controller out in a test mode that emulates the typical load on the disk subsystem of a file and web server.

The file server emulation comes first.

This table can be represented graphically like follows:

There are only 20% of write requests in this pattern, so all the arrays have good results. The RAID0 arrays show a very good scalability in speed relative to the number of disks per array. The speeds of the RAID1 and RAID10 are close to the speeds of the two- and four-disk RAID0, respectively. This means that the algorithm of optimized reading from a mirror works fine here. The RAID5 and RAID6 have good results, too.

We will compare the different arrays by calculating their performance ratings. All loads are equally probable, so the overall rating is the average speed of the array under all possible loads.

The four-disk RAID0 enjoys a big advantage over the rest of the arrays. The RAID10 is somewhat slower, yet holds the honorable second place. The RAID5 and RAID6 are a little behind the three-disk RAID0. What’s interesting, the RAID6 has a higher rating than the four-disk RAID5. The RAID1 takes the last but one place, but is not far from the single drive.

 
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